Weight Loss and Appetite Control in Women

Fasting diets: what are the impacts on eating behaviors, sleep, mood, and well-being?

Fasting diets (FDs) have drawn great attention concerning their contribution to health and disease over the last decade. Despite considerable interest in FDs, the effect of fasting diets on eating behaviors, sleep, and mood-essential components of diet satisfaction and mental health- has not been addressed comprehensively. Understanding the critical role that fasting plays in these elements will open up potential treatment avenues that have not yet been explored. The aim of the present paper was to conduct a comprehensive critical review exploring the effects of fasting on eating behaviors, sleep, and mood. There is currently a lack of clarity regarding which fasting option yields the most advantageous effects, and there is also a scarcity of consistent trials that assess the effects of FDs in a comparable manner. Similarly, the effects and/or treatment options for utilizing FDs to modify eating and sleep behaviors and enhance mood are still poorly understood. Further researches aiming at understanding the impacts of various fasting regimes, providing new insights into the gut-brain axis and offering new treatment avenues for those with resistant anxiety and depression, are warranted. Alteration of eating behaviors can have lasting effects on various physiological parameters. The use of fasting cures can underpin ancient knowledge with scientific evidence to form a new approach to the prevention and treatment of problems associated with co-morbidities or challenges pertaining to eating behaviors. Therefore, a thorough examination of the various fasting regimens and how they impact disease patterns is also warranted.

Obesity-induced and weight-loss-induced physiological factors affecting weight regain

Weight regain after successful weight loss resulting from lifestyle interventions is a major challenge in the management of overweight and obesity. Knowledge of the causal mechanisms for weight regain can help researchers and clinicians to find effective strategies to tackle weight regain and reduce obesity-associated metabolic and cardiovascular complications. This Review summarizes the current understanding of a number of potential physiological mechanisms underlying weight regain after weight loss, including: the role of adipose tissue immune cells; hormonal and neuronal factors affecting hunger, satiety and reward; resting energy expenditure and adaptive thermogenesis; and lipid metabolism (lipolysis and lipid oxidation). We describe and discuss obesity-associated changes in these mechanisms, their persistence during weight loss and weight regain and their association with weight regain. Interventions to prevent or limit weight regain based on these factors, such as diet, exercise, pharmacotherapy and biomedical strategies, and current knowledge on the effectiveness of these interventions are also reviewed.

No Evidence That Circulating GLP-1 or PYY Are Associated with Increased Satiety during Low Energy Diet-Induced Weight Loss: Modelling Biomarkers of Appetite

Bariatric surgery and pharmacology treatments increase circulating glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), in turn promoting satiety and body weight (BW) loss. However, the utility of GLP-1 and PYY in predicting appetite response during dietary interventions remains unsubstantiated. This study investigated whether the decrease in hunger observed following low energy diet (LED)-induced weight loss was associated with increased circulating 'satiety peptides', and/or associated changes in glucose, glucoregulatory peptides or amino acids (AAs). In total, 121 women with obesity underwent an 8-week LED intervention, of which 32 completed an appetite assessment via a preload challenge at both Week 0 and Week 8, and are reported here. Visual analogue scales (VAS) were administered to assess appetite-related responses, and blood samples were collected over 210 min post-preload. The area under the curve (AUC_0-210), incremental AUC (iAUC_0-210), and change from Week 0 to Week 8 (∆) were calculated. Multiple linear regression was used to test the association between VAS-appetite responses and blood biomarkers. Mean (±SEM) BW loss was 8.4 ± 0.5 kg (-8%). Unexpectedly, the decrease in ∆AUC_0-210 hunger was best associated with decreased ∆AUC_0-210 GLP-1, GIP, and valine (p < 0.05, all), and increased ∆AUC_0-210 glycine and proline (p < 0.05, both). The majority of associations remained significant after adjusting for BW and fat-free mass loss. There was no evidence that changes in circulating GLP-1 or PYY were predictive of changes in appetite-related responses. The modelling suggested that other putative blood biomarkers of appetite, such as AAs, should be further investigated in future larger longitudinal dietary studies.

The effects of resistance exercise on appetite sensations, appetite related hormones and energy intake in hormone receptor-positive breast cancer survivors

Appetite is a determinant of dietary intake and is impacted by sex hormones, exercise, and body composition among individuals without chronic conditions. Whether appetite is altered by exercise in the context of estrogen suppression and cancer survivorship is unknown. This randomized cross-over study compared appetite and ad libitum energy intake (EI) after acute resistance exercise (REx) versus sedentary (SED) conditions and in relation to body composition and resting metabolic rate (RMR) in breast cancer survivors (BCS). Physically inactive premenopausal females with previous stage I-III estrogen receptor-positive breast cancer completed a single bout of REx or SED 35 minutes after a standardized breakfast meal. Appetite visual analog scales and hormones (total ghrelin and peptide-YY [PYY]) were measured before and 30, 90, 120, 150, and 180 minutes post-meal and expressed as area under the curve (AUC). Participants were offered a buffet-type meal 180 minutes after breakfast to assess ad libitum EI. Body composition (dual X-ray absorptiometry) and RMR (indirect calorimetry) were measured during a separate visit. Sixteen BCS were included (age: 46 ± 2 y, BMI: 24.9 ± 1.0 kg/m²). There were no differences in appetite ratings or EI between conditions. There were no differences in appetite hormone AUC, but REx resulted in lower ghrelin 120 (-85 ± 39 pg/mL, p = 0.031) and 180 (-114 ± 43 pg/mL, p = 0.018) minutes post-breakfast and higher PYY 90 (21 ± 10 pg/mL, p = 0.028) and 120 (14 ± 7 pg/mL, p = 0.041) minutes post-breakfast. Fat-free mass and RMR negatively correlated with hunger and prospective food consumption AUC after SED, but not REx. In sum, a single REx bout temporarily reduces orexigenic and increases anorexic appetite hormones, but not acute subjective appetite sensations or EI.

Morning individuals in Saudi Arabia have higher self-regulation of eating behavior compared to evening types

Chronotype is a manifestation of an individual's circadian system, which can be presented as a preference for morningness or eveningness. Evening chronotype has been linked to unhealthy dietary habits. These habits are partially from poor self-regulation of eating behavior (SREB). SREB is a goal-directed process that helps resist food temptation and achieve desired dietary outcomes. It is unclear whether chronotype is associated with SREB. This study aims to investigate the association between chronotypes and SREB. A total of 599 adults (18-50 years) enrolled in this cross-sectional study. Participants received an online questionnaire that collected sociodemographic, anthropometrics, chronotype through the validated reduced Morningness-Eveningness Questionnaire (rMEQ) and SREB using the SREB Questionnaire. ANOVA, Chi-square and multivariate logistic regression were used. In adjusted models, morning types had 85% higher SREB compared to evening types (p = 0.003, OR = 1.85). Evening types found fried foods (p = 0.003), chips (p = 0.005) and French fries (p = 0.018) more tempting than morning types. These findings show a link between chronotype and SREB. Strategies focusing on SREB may help evening types improve dietary habits. Further studies are required to clarify the underlying mechanisms for these associations. This may have important implications for lifestyle and behavioral change policy.

Metabolic Slowing Vanished 5 Years After Sleeve Gastrectomy in Patients With Obesity and Prediabetes/Diabetes

BACKGROUND

Resting energy expenditure (REE) decreases after weight loss more than expected according to body composition changes. Metabolic adaptation (MA) or metabolic slowing represents the difference between measured (m) and predicted (p) REE, and it is not clear whether it persists in the long-term. The aim of this study is to evaluate MA occurring 1 year (V1) and 5 years (V5) after laparoscopic sleeve gastrectomy (LSG) in patients with obesity and normal glucose tolerance, prediabetes (preDM) and type 2 diabetes (T2DM).

METHODS

We reassessed 37 patients (14 males/23 females) of 44.8 ± 10 years old, since they registered all the biochemical, body composition, and REE assessments at baseline (V0), V1, and V5. Physical activity (PA) was assessed by interview and questionnaire.

RESULTS

Patients displayed a percentage of weight loss of 31.5 ± 7.4% at V1 and a weight regain of 8.9 ± 7.5% at V5. Comparing V1 and V5, fat mass showed a slight increase (P = 0.011), while free fat mass remained unchanged (P = 0.304). PA improved at V1 (P < 0.001), remaining stable at V5 (P = 0.9). Measured REE (mREE) displayed a 31.2% reduction with a corresponding decrease of predicted REE (pREE) of 21.4% at V1, compared with V0 (P = 0.005), confirming a significant MA at V1. Conversely, no difference between mREE and pREE was observed at V5 (P = 0.112).

CONCLUSION

Our results suggested that only patients with preDM and T2DM displayed MA at V1, which vanished 5 years after LSG. Patients who practiced more PA prevent MA after surgery-induced wight loss.

The effects of acute exercise on appetite and energy intake in men and women

PURPOSE

To compare energy intake (EI) and appetite regulation responses between men and women following acute bouts of aerobic (AEx), resistance exercise (REx), and a sedentary control (CON).

METHODS

Men and women (n = 24; 50% male) with overweight/obesity, matched on age (32.3 ± 2 vs. 36.8 ± 2 yrs, p = 0.14) and BMI (28.1 ± 1.2 vs 29.0 ± 1.5 kg/m2, p = 0.64) completed 3 conditions: 1) AEx (65-70% of age-predicted maximum heart rate for 45 min); 2) REx (1-set to failure on 12 exercises); and 3) CON. Each condition was initiated in the post-prandial state (35 min following consumption of a standardized breakfast). Appetite (visual analog scale for hunger, satiety, and prospective food consumption [PFC]) and hormones (ghrelin, PYY, and GLP-1) were measured in the fasted state and every 30 min post-prandially for 3 h. Post-exercise ad libitum EI at the lunch meal was also measured.

RESULTS

Men reported higher levels of hunger compared to women across all study conditions (AEx: Men: 7815.00 ± 368.3; Women: 5428.50 ± 440.0 mm x 180 min; p = 0.025; REx: Men: 7110.00 ± 548.4; Women: 6086.25 ± 482.9 mm x 180 min; p = 0.427; CON: Men: 8315.00 ± 429.8; Women: 5311.25 ± 543.1 mm x 180 min; p = 0.021) and consumed a greater absolute caloric load than women at the ad libitum lunch meal (AEx: Men: 1021.6 ± 105.4; Women: 851.7 ± 70.5 kcals; p = 0.20; REx: Men: 1114.7 ± 104.0; Women: 867.7 ± 76.4 kcals; p = 0.07; CON: Men: 1087.0 ± 98.8; Women: 800.5 ± 102.3 kcals; p = 0.06). However, when adjusted for relative energy needs, there was no difference in relative ad libitum EI observed between men and women. No differences in Area Under the Curve for Satiety, PFC, ghrelin, PYY, and GLP-1 were noted between men and women following acute exercise (all p > 0.05).

CONCLUSIONS

These data suggest that women report lower ratings of appetite following an acute bout of exercise or sedentary time when compared to men, yet have similar relative EI. Future work is needed to examine whether sex-based differences in appetite regulation and EI are present with chronic exercise of differing modalities.

Rolling out physical exercise and energy homeostasis: Focus on hypothalamic circuitries

Energy balance is the fine regulation of energy expenditure and energy intake. Negative energy balance causes body weight loss, while positive energy balance promotes weight gain. Modern societies offer a maladapted way of life, where easy access to palatable foods and the lack of opportunities to perform physical activity are considered the roots of the obesity pandemic. Physical exercise increases energy expenditure and, consequently, is supposed to promote weight loss. Paradoxically, physical exercise acutely drives anorexigenic-like effects, but the mechanisms are still poorly understood. Using an evolutionary background, this review aims to highlight the potential involvement of the melanocortin system and other hypothalamic neural circuitries regulating energy balance during and after physical exercise. The physiological significance of these changes will be explored, and possible signalling agents will be addressed. The knowledge discussed here might be important for clarifying obesity aetiology as well as new therapeutic approaches for body weight loss.

Postprandial glycaemic dips predict appetite and energy intake in healthy individuals

Understanding how to modulate appetite in humans is key to developing successful weight loss interventions. Here, we showed that postprandial glucose dips 2-3 h after a meal are a better predictor of postprandial self-reported hunger and subsequent energy intake than peak glucose at 0-2 h and glucose incremental area under the blood glucose curve at 0-2 h. We explore the links among postprandial glucose, appetite and subsequent energy intake in 1,070 participants from a UK exploratory and US validation cohort, who consumed 8,624 standardized meals followed by 71,715 ad libitum meals, using continuous glucose monitors to record postprandial glycaemia. For participants eating each of the standardized meals, the average postprandial glucose dip at 2-3 h relative to baseline level predicted an increase in hunger at 2-3 h (r = 0.16, P < 0.001), shorter time until next meal (r = -0.14, P < 0.001), greater energy intake at 3-4 h (r = 0.19, P < 0.001) and greater energy intake at 24 h (r = 0.27, P < 0.001). Results were directionally consistent in the US validation cohort. These data provide a quantitative assessment of the relevance of postprandial glycaemia in appetite and energy intake modulation.

From famine to therapeutic weight loss: Hunger, psychological responses, and energy balance-related behaviors

Understanding physiological and behavioral responses to energy imbalances is important for the management of overweight/obesity and undernutrition. Changes in body composition and physiological functions associated with energy imbalances provide the structural and functional context in which to consider psychological and behavioral responses. Compensatory changes in physiology and behavior are more pronounced in response to negative than positive energy balances. The physiological and psychological impact of weight loss (WL) occur on a continuum determined by (i) the degree of energy deficit (ED), (ii) its duration, (iii) body composition at the onset of the energy deficit, and (iv) the psychosocial environment in which it occurs. Therapeutic WL and famine/semistarvation both involve prolonged EDs, which are sometimes similar in magnitude. The key differences are that (i) the body mass index (BMI) of most famine victims is lower at the onset of the ED, (ii) therapeutic WL is intentional and (iii) famines are typically longer in duration (partly due to the voluntary nature of therapeutic WL and disengagement with WL interventions). The changes in psychological outcomes, motivation to eat, and energy intake in therapeutic WL are often modest (bearing in mind the nature of the measures used) and can be difficult to detect but are quantitatively significant over time. As WL progresses, these changes become more marked. It appears that extensive WL beyond 10%-20% in lean individuals has profound effects on body composition and physiological function. At this level of WL, there is a marked erosion of psychological functioning, which appears to run in parallel to WL. Psychological resources dwindle and become increasingly focused on alleviating escalating hunger and food seeking behavior. Functional changes in fat-free mass, characterized by catabolism of skeletal muscle and organs may be involved in the drive to eat associated with semistarvation. Higher levels of body fat mass may act as a buffer to protect fat-free mass, functional integrity and limit compensatory changes in energy balance behaviors. The increase in appetite that accompanies therapeutic WL appears to be very different to the intense and all-consuming drive to eat that occurs during prolonged semistarvation. The mechanisms may also differ but are not well understood, and longitudinal comparisons of the relationship between body structure, function, and behavior in response to differing EDs in those with higher and lower BMIs are currently lacking.

Physiology of weight regain: Lessons from the classic Minnesota Starvation Experiment on human body composition regulation

Since its publication in 1950, the Biology of Human Starvation, which describes the classic longitudinal Minnesota Experiment of semistarvation and refeeding in healthy young men, has been the undisputed source of scientific reference about the impact of long-term food deprivation on human physiology and behavior. It has been a guide in developing famine and refugee relief programs for international agencies, in exploring the effects of food deprivation on the cognitive and social functioning of those with anorexia nervosa and bulimia nervosa, and in gaining insights into metabolic adaptations that undermine obesity therapy and cachexia rehabilitation. In more recent decades, the application of a systems approach to the analysis of its data on longitudinal changes in body composition, basal metabolic rate, and food intake during the 24 weeks of semistarvation and 20 weeks of refeeding has provided rare insights into the multitude of control systems that govern the regulation of body composition during weight regain. These have underscored an internal (autoregulatory) control of lean-fat partitioning (highly sensitive to initial adiposity), which operates during weight loss and weight regain and revealed the existence of feedback loops between changes in body composition and the control of food intake and adaptive thermogenesis for the purpose of accelerating the recovery of fat mass and fat-free mass. This paper highlights the general features and design of this grueling experiment of simulated famine that has allowed the unmasking of fundamental control systems in human body composition autoregulation. The integration of its outcomes constitutes the "famine reactions" that drive the normal physiology of weight regain and obesity relapse and provides a mechanistic "autoregulation-based" explanation of how dieting and weight cycling, transition to sedentarity, or developmental programming may predispose to obesity. It also provides a system physiology framework for research toward elucidating proteinstatic and adipostatic mechanisms that control hunger-appetite and adaptive thermogenesis, with major implications for a better understanding (and management) of cachexia, obesity, and cardiometabolic diseases.

Food Liking but Not Wanting Decreases after Controlled Intermittent or Continuous Energy Restriction to ≥5% Weight Loss in Women with Overweight/Obesity

Food reward (i.e., liking and wanting) has been shown to decrease after different types of weight management interventions. However, it is unknown whether specific dietary modalities (continuous (CER) vs. intermittent (IER) energy restriction) have differing effects on liking and implicit wanting after weight loss (WL) and whether these changes are sustained after 1-year of no-contact. Women with overweight or obesity (age 18–55 years) were randomly allocated to controlled-feeding CER (25% daily energy restriction) or IER (alternating ad libitum and 75% energy restriction days). Study visits were conducted at baseline, post-WL (to ≥5% WL within 12 weeks) and 1-year post-WL. The main outcomes were liking and implicit wanting for 4 categories of common food varying in fat and taste assessed by the Leeds Food Preference Questionnaire. Linear mixed models were conducted on the 30 participants achieving ≥5% WL and 15 returners. After an initial WL of −5.1 ± 0.2 kg, after 1-year 2.6 ± 0.5 kg were regained. Liking but not wanting decreased after WL. Food reward after 1-year did not differ from baseline, but the high loss to follow-up prevents generalization. IER and CER did not differ in their effects on food reward during WL or at 1-year follow-up.

Acute postprandial effect of yacon syrup ingestion on appetite: A double blind randomized crossover clinical trial

Yacon syrup is a rich source of fructooligosaccharides (FOS); however, its diet supplementation effect on subjective sensation and appetite biomarkers in human is still unknown. This study aimed to evaluate the acute postprandial effect of yacon syrup ingestion on appetite. The double-blind crossover clinical trial was carried out with 40 adult women: 20 eutrophic and 20 obese grade I. On each day, the first blood collection was performed after a 12-h fast. Then, the volunteers ingested either intervention A (breakfast + 40 g of placebo) or intervention B (breakfast + 40 g of yacon syrup, containing 14 g of FOS). New aliquots of blood were collected at 45, 60, 90, 120, and 180 min. Appetite was assessed by estimating ghrelin and glucagon-like peptide-1 (GLP-1) levels and by assessing subjective appetite sensation. Analysis was performed using two-way ANOVA, followed by Bonferroni's multiple comparison test. No effect of yacon syrup was observed on postprandial ghrelin and GLP-1 levels at all times evaluated. Similar observations were made after stratifying the analysis by BMI (body mass index) (eutrophic and obese). The effect of yacon syrup on postprandial subjective sensations of hunger, satiety, fullness, and desire to eat was not evident in the total group of women evaluated and even after BMI stratification. We concluded that yacon syrup had no effect on postprandial ghrelin and GLP-1 levels and on the subjective appetite sensation in young adult women.

Using pre-prandial blood glucose to assess eating in the absence of hunger in free-living individuals

Our ability to understand and intervene on eating in the absence of hunger (EAH) as it occurs in peoples' natural environments is hindered by biased methods that lack ecological validity. One promising indicator of EAH that does not rely on self-report and is easily assessed in free-living individuals is glucose. Here, we hypothesize that elevated pre-prandial blood glucose concentrations (PPBG), which reflect a source of readily-available, short-term energy, are a biological indicator of EAH. This was a 7-day observational study of N = 41, 18-24 year old men and women with BMI < 25 kg/m² (60%) or BMI ≥ 25 kg/m² (40%). We collected data using ecological momentary assessment from people in their natural environments. We defined EAH by self-report (perceived EAH) and by PPBG thresholds using two methods (standardized, PPBG < 85 mg/dl; personalized, PPBG < individual fasting levels). Multilevel modeling was used to analyze the data. N = 963 eating events were reported. There were significantly (p < .05) fewer perceived EAH events (25%) as compared to standardized (62%) and personalized PPBG-defined EAH events (51%). Consistent with published literature, perceived EAH was more likely to occur at a higher PPBG (p < .01), particularly among participants with a BMI ≥ 25 kg/m² (p_int < .01). Additionally, discordance between perceived EAH and PPBG-defined EAH, indicating a perception of hunger at an eating event when PPBS was elevated, was less likely among participants with a BMI < 25 kg/m² vs. those with a BMI ≥ 25 kg/m² (p_int < .01) as well as at snacks vs. meals (p_int < .01). These findings provide preliminary support for using PPBG as a biological indicator of EAH in free-living individuals.

Developing evidence-based behavioural strategies to overcome physiological resistance to weight loss in the general population

Physiological and behavioural systems are tolerant of excess energy intake and responsive to energy deficits. Weight loss (WL) changes body structure, physiological function and energy balance (EB) behaviours, which resist further WL and promote subsequent weight regain. Measuring and understanding the response of EB systems to energy deficits is important for developing evidence-based behaviour change interventions for longer-term weight management. Currently, behaviour change approaches for longer-term WL show modest effect sizes. Self-regulation of EB behaviours (e.g. goal setting, action plans, self-monitoring, relapse prevention plans) and aspects of motivation are important for WL maintenance. Stress management, emotion regulation and food hedonics may also be important for relapse prevention, but the evidence is less concrete. Although much is known about the effects of WL on physiological and psychological function, little is known about the way these dynamic changes affect human EB behaviours. Key areas of future importance include (i) improved methods for detailed tracking of energy expenditure, balance and by subtraction intake, using digital technologies, (ii) how WL impacts body structure, function and subsequent EB behaviours, (iii) how behaviour change approaches can overcome physiological resistance to WL and (iv) who is likely to maintain WL or relapse. Modelling physiological and psychological moderators and mediators of EB-related behaviours is central to understanding and improving longer-term weight and health outcomes in the general population.

Associations between the proportion of fat-free mass loss during weight loss, changes in appetite, and subsequent weight change: results from a randomized 2-stage dietary intervention trial

BACKGROUND

Dynamic changes in body composition which occur during weight loss may have an influential role on subsequent energy balance behaviors and weight.

OBJECTIVES

The aim of this article is to consider the effect of proportionate changes in body composition during weight loss on subsequent changes in appetite and weight outcomes at 26 wk in individuals engaged in a weight loss maintenance intervention.

METHODS

A subgroup of the Diet, Obesity, and Genes (DiOGenes) study (n = 209) was recruited from 3 European countries. Participants underwent an 8-wk low-calorie diet (LCD) resulting in ≥8% body weight loss, during which changes in body composition (by DXA) and appetite (by visual analog scale appetite perceptions in response to a fixed test meal) were measured. Participants were randomly assigned into 5 weight loss maintenance diets based on protein and glycemic index content and followed up for 26 wk. We investigated associations between proportionate fat-free mass (FFM) loss (%FFML) during weight loss and 1) weight outcomes at 26 wk and 2) changes in appetite perceptions.

RESULTS

During the LCD, participants lost a mean ± SD of 11.2 ± 3.5 kg, of which 30.4% was FFM. After adjustment, there was a tendency for %FFML to predict weight regain in the whole group (β: 0.041; 95% CI: -0.001, 0.08; P = 0.055), which was significant in men (β: 0.09; 95% CI: 0.02, 0.15; P = 0.009) but not women (β: 0.01; 95% CI: -0.04, 0.07; P = 0.69). Associations between %FFML and change in appetite perceptions during weight loss were inconsistent. The strongest observations were in men for hunger (r = 0.69, P = 0.002) and desire to eat (r = 0.61, P = 0.009), with some tendencies in the whole group and no associations in women.

CONCLUSIONS

Our results suggest that composition of weight loss may have functional importance for energy balance regulation, with greater losses of FFM potentially being associated with increased weight regain and appetite. This trial was registered at clinicaltrials.gov as NCT00390637.

Associations between the rate, amount, and composition of weight loss as predictors of spontaneous weight regain in adults achieving clinically significant weight loss: A systematic review and meta-regression

Weight regain following weight loss is common although little is known regarding the associations between amount, rate, and composition of weight loss and weight regain. Forty-three studies (52 groups; n = 2379) with longitudinal body composition measurements were identified in which weight loss (≥5%) and subsequent weight regain (≥2%) occurred. Data were synthesized for changes in weight and body composition. Meta-regression models were used to investigate associations between amount, rate, and composition of weight loss and weight regain. Individuals lost 10.9% of their body weight over 13 weeks composed of 19.6% fat-free mass, followed by a regain of 5.4% body weight over 44 weeks composed of 21.6% fat-free mass. Associations between the amount (P < 0.001) and rate (P = 0.049) of weight loss and their interaction (P = 0.042) with weight regain were observed. Fat-free mass (P = 0.017) and fat mass (P < 0.001) loss both predicted weight regain although the effect of fat-free mass was attenuated following adjustment. The amount (P < 0.001), but not the rate of weight loss (P = 0.150), was associated with fat-free mass loss. The amount and rate of weight loss were significant and interacting factors associated with weight regain. Loss of fat-free mass and fat mass explained greater variance in weight regain than weight loss alone.

Compensation in response to energy deficits induced by exercise or diet

Obesity is an extremely resilient condition. Weight loss is most challenging, and weight recidivism is rampant. There is accumulating evidence highlighting that energy deficits meant to produce increased mobilization of energy stores trigger a number of somewhat persistent adaptations that together increase the drive to eat and decrease energy output. These adaptations ostensibly enable a context where the likelihood of energy compensation is heightened. In fact, energy compensation is present for both diet and exercise induced energy deficits although at different magnitudes. For the most part, the energy compensation in response to exercise induced energy deficits seems to be larger. Interestingly, energy compensation appears to be greater for longer interventions, an effect independent of whether the energy deficit is induced through diet or exercise. The latter suggests that the increased drive to eat and the reduced energy expenditure that accompany weight loss might be successfully fought off initially. However, with time there seems to be increasing erosion of the behaviours that initially opposed adaptations to weight loss and increased energy compensation progressively sets in. Under such conditions, it would seem prudent to propose weight loss targets that align with a level of behaviour modifications that can be sustained indefinitely.

Weight Suppression in Eating Disorders: a Research and Conceptual Update

PURPOSE OF REVIEW

Weight suppression, the discrepancy between an individual's highest past weight at adult height and his or her current weight, is related to many characteristics of individuals with eating disorders. This paper reviews research findings from the past 5 years, draws several implications regarding the mechanism underlying these effects, and proposes new approaches to measuring weight suppression.

RECENT FINDINGS

Studies were reviewed under the categories of anorexia nervosa, bulimia nervosa, and mixed or miscellaneous samples, with more studies falling into the last category than in the first two. Recent findings have continued to show that weight suppression is related to a wide variety of biological and behavioral features in both diagnosed and sub-clinical samples. Weight suppression promotes weight gain which is anathema to individuals with eating disorders, putting them in a biobehavioral bind that appears to prolong their disorder. Priorities for future research are to understand the mechanisms underlying the effects of weight suppression, evaluate new ways of defining weight suppression, and study its implications for modifying treatment.

Influence of Muscle Mass and Outdoor Environmental Factors on Appetite and Satiety Feeling in Young Japanese Women

Research on the influence of relationships among satiety, muscle mass, and outdoor environmental factors is sparse. In this work the relationships among satiety feeling, body composition, and outdoor environmental factors on eating in healthy young Japanese women are investigated. Fifty three (53) women were examined over an approximately 2-year period. All participants ate the same lunch; feelings of satiety and body composition were measured before and immediately after lunch. Satiety was assessed using a visual analog scale. Outdoor environmental factors were recorded at the time of measurement. Results showed that satiety before lunch decreased with increased muscle mass and decreased humidity (p < 0.05). The Δ satiety increased on eating with increased outdoor temperature (p < 0.05). The Δ satiety with high outdoor temperature was significantly greater than with low outdoor temperature (p = 0.005). Decreased muscle mass more influenced Δ satiety with respect to outdoor temperature than increased muscle mass (p = 0.007). The results suggest that increased muscle mass and decreased humidity increase hunger (unlike satiety) before eating. The findings also show that outdoor temperature clearly influences the magnitude of satiety on eating. Increasing muscle mass may be useful for satiety control at various outdoor temperatures in young women.

Leptin Mediates a Glucose-Fatty Acid Cycle to Maintain Glucose Homeostasis in Starvation

The transition from the fed to the fasted state necessitates a shift from carbohydrate to fat metabolism that is thought to be mostly orchestrated by reductions in plasma insulin concentrations. Here, we show in awake rats that insulinopenia per se does not cause this transition but that both hypoleptinemia and insulinopenia are necessary. Furthermore, we show that hypoleptinemia mediates a glucose-fatty acid cycle through activation of the hypothalamic-pituitary-adrenal axis, resulting in increased white adipose tissue (WAT) lipolysis rates and increased hepatic acetyl-coenzyme A (CoA) content, which are essential to maintain gluconeogenesis during starvation. We also show that in prolonged starvation, substrate limitation due to reduced rates of glucose-alanine cycling lowers rates of hepatic mitochondrial anaplerosis, oxidation, and gluconeogenesis. Taken together, these data identify a leptin-mediated glucose-fatty acid cycle that integrates responses of the muscle, WAT, and liver to promote a shift from carbohydrate to fat oxidation and maintain glucose homeostasis during starvation.